Alternative Room Disinfection Modalities –Pros and Cons - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 198

reduction to the fumigation procedure [ 30 ]. The authors noted that the infection rate
was already below the hospital's action threshold of 1.1 infections per 1,000 patient
days the month before the intervention started. It was also observed that during
the last 3 months of the HPV intervention, there was a steady increase in incidence.
The last month's rate was above the hospital's action threshold. If fumigation was
an effective infection control method, then one would expect consistently low
incident rates throughout the 10-month intervention period.
The decision to use fumigation in occupied buildings must be carefully con-
sidered, since a breach in containment could injure patients, visitors, or personnel
and, in the case of chlorine dioxide and hydrogen peroxide, damage surfaces.
To avoid operator errors, the safest approach would be to evacuate during fumi-
gation. However, this would be costly, and relocating displaced patients should be
carefully considered to assure there is adequate bed-capacity in other facilities.
Generally, a cost-benefit analysis should not be performed until both efficacy
and effectiveness have been firmed demonstrated. Unfortunately, in the case
of chemical fumigation, safety and other effectiveness concerns are unresolved.
Nevertheless, Otter et al., examined the feasibility of routinely using hydrogen
peroxide fumigation [ 102 ]. They noted that the time to pre-clean, prepare and
administer the fumigant, and wait for the vapor to clear took 4-5 h which was
more than 3 times longer than disinfecting with dilute bleach solution. They also
noted that as hospital occupancy rates went up, the difficulty in scheduling a time
consuming fumigation procedure increased, and more rooms targeted for fumiga-
tion were missed. At this point, it is hard to see how busy modern medical facilities
could afford the loss of room space during fumigation.
Complex environmental factors may limit the effectiveness of ultraviolet
irradiation. To be effective, RH must be within a narrow range (50-60 %)
[ 87 , 88 ]. Also, source to target distance will influence beam intensity, duration of
exposure must be sufficient to inactivate microbes, and in the case of upper air
disinfection, insufficient air movement and turbulence will significantly reduce
effectiveness [ 72 ]. The type of organism varies significantly in susceptibility to
UVC disinfection. For example, double stranded viruses were more resistant than
single DNA viruses, bacterial and fungal spores are highly resistant to inactivation,
and photoreactivation has been demonstrated [ 84 , 87 , 96 ]. The use of unshielded
UVC lamps significantly increases the likelihood of worker, patient or visitor over-
exposure. While the depth of penetration of UVC reduces its potential to cause
cancer, the U.S. National Toxicological Program lists UVC as an agent “ reasonably
anticipated to be a human carcinogen ” based on limited human cell data and
sufficient evidence in animal studies [ 94 ]. The most common effects of UVC
exposure are photoketaoconjunctivitis (snow blindness) and photodermatitis (sun
burn) [ 68 ]. According to Memarzadeh, the use of germicidal UV as a means of
infection control must be evaluated under controlled experimental conditions,
rather than reliance on observational and retrospective studies [ 103 ]. Results from
poorly controlled observational studies would be subject to the Hawthorne effect.
In summary, chemical fumigation of a healthcare facility has merit under certain
conditions such as in response to a bioterrorism attack [ 59 ]. If a building is heavily